The invention relates to a device for reducing longitudinal dynamic instabilities of vehicles, in particular back and forth movements of cargo and the uncontrolled periodic feeding of gas, having means to adjust the deflection (movement) of a setting device for the fuel-air mixture which is to be fed to an internal combustion engine of the vehicle.
The longitudinal dynamic instabilities of the vehicle express themselves in the manner that upon intentional acceleration by depression of the gas pedal, undesired periodic changes in acceleration are also brought about. The accelerations are transmitted to the driver, who thus brings about an undesired change in the position of the gas pedal. The entire oscillating system, which the vehicle comprises with its elasticities in the drive train, masses to be accelerated and moments of inertia, as well as the power output of the internal combustion engine which corresponds to the operating point on the torque/speed-of-rotation curve and other factors, can be dynamically unstable. In this way an oscillation can build up with which, in the extreme case, almost the entire path of displacement of the gas pedal is unintentionally moved over (bonanza effect).
In order to remedy this undesired phenomenon which occurs, in particular, in the case of internal combustion engines having a steep torque/speed-of-rotation curve, it has already been attempted to dampen the longitudinal oscillations of the vehicle/driver system by connecting the gas pedal via a delay member to the setting member which controls the fuel/air mixture of the internal combustion engine. The delay member has been developed in particular as a dashpot. This type of damping has the drawback that even those displacements of the gas pedal which are intended by the driver are also converted only with delay into corresponding positions of the setting member. As a result of this damping device in the connection between the gas pedal and the setting device, an undesired delay thus takes place in the response of the internal combustion engine. In addition, there are difficulties in tuning the damping device since the periodic oscillation which is to be damped in the connection between the gas pedal and the engine is dependent on the type of vehicle and--for a given type of vehicle--on the gear in which it is traveling. Furthermore, this known method for apparently improving the longitudinal stability of the vehicle is basically ineffective when the disturbing excitations of the oscillations are not introduced via the gas pedal but at other places, for instance by shifting or clutching operations or irregularities in the roadbed.
It is an object of the invention to create a device which effectively reduces the injurious effects of the longitudinal dynamic instabilities of the vehicle regardless of the point of action of the disturbing influences, the parameters of which device can be adjusted in a non-critical manner and which does not perceptibly impair the response of the internal combustion engine to intended actuation of the gas pedal.